The synaptic organization and physiological responses of retinal neurons are fairly well understood. However, little is known about the role of glial cells and their interactions with retinal neurons. We are interested in the function of glial cells, particularly the Muller cells, in the vertebrate retina. In the last few years, we have studied both metabolic and ionic properties of Muller cells. The present research proposal is concerned with characterization of Muller cell-specific antigens using monoclonal antibodies as molecular probes. In addition, we also plan to study the organization and expression of genes coding for certain glial-specific proteins. Our specific objectives are (1) to obtain murine monoclonal antibodies which are specific to Muller cells from embryonic and adult retinas; (2) to isolate the gene coding for the cellular retinal-binding protein (CRALBP) present in Muller cells, by screening a Lambdagt10 retinal cDNA library with a synthetic oligonucleotide probe prepared from the known primary amino acid sequence of the protein; (3) to characterize novel mRNAs that are expressed in Muller cells undergoing reactive gliosis, using the technique of differential cDNA hybridization; and (4) to examine the developmental expression of the glial-specific proteins -- Carbonic anhydrase II, Glial Fibrillary Acidic Protein (GFAP), and Glutamine synthetase.